ther circumstantial or testimonial evidence
sufficient to prove the eternity of duration of the present state of
nature, you must have an eternity of witnesses or an infinity of
circumstances, and neither of these is attainable. It is utterly
impossible that such evidence should be carried beyond a certain point of
time; and all that could be said, at most, would be, that, so far as the
evidence could be traced, there was nothing to contradict the hypothesis.
But when you look, not to the testimonial evidence,--which, considering
the relative insignificance of the antiquity of human records, might not
be good for much in this case,--but to the circumstantial evidence, then
you find that this hypothesis is absolutely incompatible with such
evidence as we have; which is of so plain and so simple a character that
it is impossible in any way to escape from the conclusions which it forces
upon us.

You are, doubtless, all aware that the outer substance of the earth, which
alone is accessible to direct observation, is not of a homogeneous
character, but that it is made up of a number of layers or strata. Each of
these groups represents a number of beds of sand, of stone, of clay, of
slate, and of various other materials.

On careful examination, it is found that the materials of which each of
these layers of more or less hard rock is composed are, for the most part,
of the same nature as those which are at present being formed under known
conditions on the surface of the earth. For example, the chalk, which
constitutes a great part of the Cretaceous formation in some parts of the
world, is practically identical in its physical and chemical characters
with a substance which is now being formed at the bottom of the Atlantic
Ocean, and covers an enormous area; other beds of rock are comparable with
the sands which are being formed upon sea-shores, packed together, and so
on. Thus, omitting rocks of igneous origin, it is demonstrable that all
these beds of stone, of which a total of not less than seventy thousand
feet is known, have been formed by natural agencies, either out of the
waste and washing of the dry land, or else by the accumulation of the
exuviae of plants and animals. Many of these strata are full of such
exuviae--the so-called "fossils." Remains of thousands of species of
animals and plants, as perfectly recognizable as those of existing forms
of life which you meet with in museums, or as the shells which you pick